The present invention relates to an oligosiloxane and more particularly to an oligosiloxane containing both silicon-bonded alkoxy and monovalent hydrocarbyl groups, wherein each hydrocarbyl group is free of aliphatic unsaturation and has at least 11 carbon atoms. This invention also relates to a method of preparing an alkoxy-functional oligosiloxane.
Silicon-bonded alkoxy-functional oligosiloxanes are disclosed in Japanese Laid Open (Kokai or Unexamined) Patent Application Numbers Hei 3-197486 (197,486/1991), Hei 4-7305 (7,305/1992), and Hei 5-70514 (70,514/1993). However, none of the references teach an alkoxy-functional oligosiloxane containing a monovalent hydrocarbyl group free of aliphatic unsaturation and having at least 11 carbon atoms.
Methods for preparing silicon-bonded alkoxy-functional oligosiloxanes are known. For example, Japanese Laid Open (Kokai or Unexamined) Patent Application Number Hei 3-197486 (197,486/1991) teaches the reaction of silanol-functional oligosiloxane or silane with silicon-bonded alkoxy-functional silane in the presence of the hydroxide or chloride of an alkali metal or alkaline-earth metal or in the presence of a basic metal salt. In addition, the reaction of silanol-functional silane and silicon-bonded alkoxy-functional silane in the presence of an amine compound is taught in Japanese Laid Open (Kokai or Unexamined) Patent Application Numbers Hei 4-7305 (7,305/1992) and Hei 5-70514 (70,514/1993). These methods, however, suffer from impaired yields of the desired oligosiloxane because they require the use of an unstable silanol-functional oligosiloxane or silane and because the silanol group in the starting oligosiloxane or silane undergoes intermolecular condensation with other silanol in the same reactant.
One object of the present invention is to provide novel oligosiloxanes containing both silicon-bonded alkoxy and monovalent hydrocarbyl groups, wherein each hydrocarbyl group is free of aliphatic unsaturation and has at least 11 carbon atoms. Another object of this invention is to provide a highly efficient method for synthesizing an alkoxy-functional oligosiloxane.
The present invention is directed to an oligosiloxane having the formula:
(R1O)aSi(OSiR22R3)4xe2x88x92a
wherein R1 is alkyl; each R2 is independently selected from C1 to C10 monovalent hydrocarbyl free of aliphatic unsaturation; R3 is monovalent hydrocarbyl free of aliphatic unsaturation and having at least 11 carbon atoms; and a is 1, 2, or 3.
This invention is also directed to a method of preparing an oligosiloxane having the formula:
(R1O)aSi(OSiR22R3)4xe2x88x92a
comprising reacting an oligosiloxane having the formula:
(R1O)aSi(OSiR22H)4xe2x88x92a
with a hydrocarbon containing 1 aliphatic double bond per molecule in the presence of a hydrosilylation catalyst, wherein R1 is alkyl; each R2 is independently selected from C1 to C10 monovalent hydrocarbyl free of aliphatic unsaturation; R3 is monovalent hydrocarbyl free of aliphatic unsaturation and having at least 2 carbon atoms; and a is 1, 2, or 3.
The oligosiloxanes synthesized as described above are useful as surface treatment agents for inorganic fillers and as reactive oligosiloxanes capable of reacting with silanol-functional organopolysiloxanes and hydroxyl-functional organic resins. The method of the present invention affords silicon-bonded alkoxy-functional oligosiloxanes at high efficiencies.
An oligosiloxane according to the present invention has the formula:
(R1O)aSi(OSiR22R3)4xe2x88x92a
wherein R1 is alkyl; each R2 is independently selected from C1 to C10 monovalent hydrocarbyl free of aliphatic unsaturation; R3 is monovalent hydrocarbyl free of aliphatic unsaturation and having at least 11 carbon atoms; and a is 1, 2, or 3.
Examples of alkyl groups represented by R1 include, but are not limited to, straight-chain alkyl such as methyl, ethyl, propyl, butyl, hexyl, and decyl; branched alkyl such as isopropyl, tert-butyl, and isobutyl; and cyclic alkyl such as cyclohexyl. R1 preferably is C1 to C4 alkyl and more preferably is methyl or ethyl. R2 is exemplified by straight-chain alkyl such as methyl, ethyl, propyl, butyl, hexyl, and decyl; branched alkyl such as isopropyl, tert-butyl, and isobutyl; cyclic alkyl such as cyclohexyl; aryl such as phenyl, tolyl, and xylyl; and aralkyl such as benzyl and phenethyl. R2 is preferably C1 to C4 alkyl and more preferably is methyl or ethyl. R3 is exemplified by straight-chain alkyl such as undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl; branched alkyl such as 2-methylundecyl and 1-hexylheptyl; cyclic alkyl such as cyclododecyl; and aralkyl such as 2-(2,4,6-trimethylphenyl)propyl. R3 is preferably straight-chain alkyl and more preferably is C11 to C20 straight-chain alkyl. The subscript a in the general formula under consideration can be 1, 2, or 3 and preferably is 3.
The oligosiloxanes of this invention are exemplified by the following compounds: 
The oligosiloxanes described above, because they contain silicon-bonded alkoxy and monovalent hydrocarbyl groups, wherein each hydrocarbyl group is free of aliphatic unsaturation and has at least 11 carbon atoms, are useful as surface treatment agents for inorganic fillers and as reactive oligosiloxanes capable of reacting with silanol-functional organopolysiloxanes and hydroxyl-functional organic resins.
A method according to the present invention of preparing an oligosiloxane having the formula:
(R1O)aSi(OSiR22R3)4xe2x88x92a
comprises reacting an oligosiloxane (A) having the formula:
(R1O)aSi(OSiR22R3)4xe2x88x92a
with a hydrocarbon (B) containing 1 aliphatic double bond per molecule in the presence of a hydrosilylation catalyst (C), wherein R1, R2, and subscript a are as defined and exemplified above, including the preferred embodiments thereof; R3 is monovalent hydrocarbyl free of aliphatic unsaturation and having at least 2 carbon atoms. Preferably, the monovalent hydrocarbyl groups represented by R3 have at least 11 carbon atoms.
Examples of hydrocarbyl groups represented by R3 include, but are not limited to, straight-chain aliphatic hydrocarbyl such as ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, and nonadecyl; branched aliphatic hydrocarbyl such as 1-methylbutyl, 1-ethylpropyl, 1-ethylbutyl, 2-methylundecyl, and 1,1-dimethyldecyl; cyclic aliphatic hydrocarbyl such as cyclododecyl; and aromatic hydrocarbyl such as 2-(2,4,6-trimethylphenyl)propyl. R3 is preferably straight-chain aliphatic hydrocarbyl (i.e., alkyl), more preferably is C2 to C20 straight-chain aliphatic hydrocarbyl, and most preferably is C11 to C20 straight-chain aliphatic hydrocarbyl.
The oligosiloxane (A) can itself be synthesized, for example, by the reaction of tetraalkoxysilane having the general formula Si(OR1)4, wherein R1 is alkyl, with a disiloxane having the general formula R22HSiOSiR22H, wherein each R2 is independently selected from C11 to C10 monovalent hydrocarbon groups free of aliphatic unsaturation, in the presence of a strong acid and a carboxylic acid.
The oligosiloxane (A) is exemplified by trialkoxysiloxydialkylsilanes such as trimethoxysiloxydimethylsilane, triethoxysiloxydimethylsilane, and tripropoxysiloxydimethylsilane; bis(dialkylsiloxy)dialkoxysilanes such as bis(dimethylsiloxy)dimethoxysilane, bis(dimethylsiloxy)diethoxysilane, bis(dimethylsiloxy)dipropoxysilane, and bis(dimethylsiloxy)dibutoxysilane; and tris(dialkylsiloxy)alkoxysilanes such as tris(dimethylsiloxy)methoxysilane, tris(dimethylsiloxy)ethoxysilane, tris(dimethylsiloxy)propoxysilane, and tris(dimethylsiloxy)butoxysilane.
A characteristic feature of the hydrocarbon (B) is that it contains 1 aliphatic double bond in each molecule. The molecular structure of component (B) is not critical and this component can be, for example, straight chain, branched, or cyclic. While the position of the aliphatic double bond in (B) is not critical, it is preferably present in molecular chain terminal position because of its higher reactivity in this position. Hydrocarbon (B) can be exemplified by straight-chain aliphatic hydrocarbons such as ethylene, propene, 1-butene, 2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, 3-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 6-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, and 1-eicosene; branched aliphatic hydrocarbons such as 2-methylundecene; cyclic aliphatic hydrocarbons such as cyclododecene; and aromatic hydrocarbons that contain an aliphatic double bond, such as 2-(2,4,6-trimethylphenyl)propene. The hydrocarbon (B) preferably is a straight-chain aliphatic hydrocarbon, more preferably is a C2 to C20 straight-chain aliphatic hydrocarbon, and most preferably is a C11 to C20 straight-chain aliphatic hydrocarbon.
The hydrosilylation catalyst (C) accelerates the addition in the preparative method under consideration of the silicon-bonded hydrogen in oligosiloxane (A) across the aliphatic double bond in hydrocarbon (B). This catalyst is exemplified by transition metal catalysts from Group VIII of the Periodic Table with platinum catalysts being particularly preferred. Said platinum catalysts are exemplified by chloroplatinic acid, alcohol solutions of chloroplatinic acid, olefin complexes of platinum, alkenylsiloxane complexes of platinum, and carbonyl complexes of platinum.
The molar ratio of component (B) to component (A) is not critical in the preparative method under consideration, but component (B) is preferably used at from 0.5 to 1.5 moles per 1 mole component (A) and more preferably is used in an amount equimolar with component (A).
The use of organic solvent in the preparative method under discussion is optional. When used, this organic solvent can be, for example, an aromatic such as benzene, toluene, or xylene; an aliphatic such as pentane, hexane, heptane, octane, or decane; an ether such as tetrahydrofuran, diethyl ether, or dibutyl ether; a ketone such as acetone or methyl ethyl ketone; an ester such as ethyl acetate or butyl acetate; or a chlorinated hydrocarbon such as carbon tetrachloride, trichloroethane, methylene dichloride, or chloroform.
The reaction temperature in the preparative method under discussion is also not critical and the reaction can be run at room temperature or with heating. When the reaction is run with heating, the reaction temperature is preferably from 50 to 200xc2x0 C. The progress of the reaction can be followed by gas chromatographic analysis of the reaction solution or by monitoring the reaction system for the characteristic absorption of silicon-bonded hydrogen using, for example, infrared spectroscopic analysis or nuclear magnetic resonance analysis. The reaction can be regarded as finished when the characteristic absorption of the silicon-bonded hydrogen in the reaction solution has either disappeared or is no longer changing. After completion of the reaction, the desired oligosiloxane can be recovered by removal of the unreacted components and any organic solvent.
Examples of oligosiloxanes that can be prepared using the preceding method include: 
The inventive method for producing oligosiloxanes is characterized by the ability to synthesize silicon-bonded alkoxy-functional oligosiloxanes at high efficiencies. The oligosiloxanes afforded by the preparative method of this invention, because they contain silicon-bonded alkoxy groups, are useful as surface treatment agents for inorganic fillers and as reactive oligosiloxanes capable of reacting with silanol-functional organopolysiloxanes and hydroxyl-functional organic resins.